Background
The carbon sink and greenhouse gas exchange ecosystem functions in peatlands have been and will be impacted by climate change and human disturbances (such as agricultural drainage, forestry drainage, peat mining, and restoration). How northern peatlands will function in terms of carbon sink, greenhouse gas emissions and mitigating climate change in the future with climate warming and human disturbances is unclear, because to answer this question requires a peatland ecosystem model that can work well with peatland disturbances and restoration in the context of climate change, which may alter vegetation composition and hydrology in peatlands. This significantly increases the uncertainty of evaluating the potential of peatlands as nature-based solutions and impacts the climate change policy and mitigation implementation in Canada to achieving net-zero emission by 2050. Previous studies reported that climate warming has the potential to reduce the carbon sink capacity of peatlands and even switch them to be carbon sources while potentially increasing methane emission. However, how climate warming along with elevated nitrogen and phosphorus deposition to which boreal peatlands will be exposed will interactively affect the carbon sink capacity and greenhouse gas emissions in boreal peatlands is not well understood, leading to uncertainty of projecting ecosystem function of boreal peatlands by 2050. Moreover, although natural peatlands function as a neutral or a small source of nitrous oxide, a much more potent greenhouse gas with 298 times higher global warming potential than carbon dioxide, peatlands may become a hotspot of nitrous oxide emission under the increasing nitrogen deposition and nitrogen fertilization in the disturbed and restored peatlands. Therefore, there is a need to further develop and evaluate an ecosystem-scale model that can simulate the hydrology and carbon dioxide, methane and nitrous oxide cycling for peatland disturbances and restoration under climate change. McGill Wetland Model (MWM), has been coupled with Holocene Peatland Model, a cohort peatland model that can dynamically model the peat properties of each peat cohort, and incorporate the microbial dynamics and nitrogen, phosphorus cycling in peatlands. Therefore, MWM is an ideal peatland ecosystem model to simulate the carbon dynamics at the local scale for peatland disturbances and restoration. MWM can provide detailed process understanding of peatland response to disturbance that will provide a valuable comparison to models that can be applied at regional to national scales.
Activity Outline
Further develop MWM to incorporate the following aspects:
- A new soil hydrology module that is fully coupled with the carbon dynamics of peatlands to simulate soil temperature and moisture, and water table depth
- A new module of methane and nitrous oxide cycling and dissolved organic carbon for peatlands that will function with natural as well as disturbed and restored peatlands
- A vegetation dynamics module to simulate the changes/shifts of vegetation composition in peatlands under climate change, human disturbance and restoration
Then:
- Evaluate the newly further developed and adapted MWM at a suite of natural peatland sites and disturbed peatland sites and restored peatland sites
- Run site scale simulations of undeveloped peatlands, disturbed peatlands, and restored/reclaimed and their response to climate change using difference scenarios of climate changes in the next 100 years